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Setting up Photon server

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Jay Malhotra edited this page Aug 20, 2024 · 14 revisions

THE FREE 100 CCU PHOTON LICENSE HAS BEEN DISCONTINUED AS OF SEPTEMBER 2023.

It is not possible to configure co-op unless you purchase a license. At the time of writing, the cheapest Photon license is 500 CCU for $95 a month, which requires owning an Industries Circle membership at an additional cost of $250 a month.

Photon is the technology used to provide co-op functionality for the game. It is a peer-to-peer system with the server acting as one peer. Dragalia makes use of a custom plugin attached to the Photon Server product to manage game state; client expect to receive particular properties and events from the server. The code for the plugin is in the monorepo in DragaliaAPI.Photon.Plugin.

The steps below detail how to set up a Photon server to work with the project, either for local development or production. Note that if you want to run the Photon server for local development, the solution is configured to expect the server SDK placed in the root of the repository (it is git ignored for licensing reasons).

The below instructions are for v3.2.2 of the plugin.

How to build the plugin

The plugin can be compiled from the source code provided from each release, but you must first add a reference to PhotonHivePlugin.dll, which can be downloaded as part of the Plugins SDK from Photon's website. Builds of the plugin are not provided with the releases to avoid redistributing this proprietary component.

Ensure the plugin is compiled in Release mode before deploying to production.

How to set up a Photon server

Part 1: Configuring Photon Server

  1. Follow the instructions from the Photon documentation to setting up the server. Pay particular attention to step 7 if you intend to expose the server on a public or local IP address.

  2. Place the plugin binary files in Plugins/GluonPlugin/<VERSION>/bin.

  3. Install the plugin, by editing LoadBalancing/GameServer/bin/plugin.config. Below is a sample configuration:

    <root>
    <PluginSettings Enabled="True">
        <Plugins>
            <Plugin
                    Name="GluonPlugin"
                    Version="v1"
                    AssemblyName="DragaliaAPI.Photon.Plugin.dll"
                    Type="DragaliaAPI.Photon.Plugin.GluonPluginFactory"
                    ApiServerUrl="https://dawnshard.co.uk/"
                    StateManagerUrl="https://photonstatemanager.dawnshard.co.uk/"
                    DungeonRecordMultiEndpoint="dungeon_record/record_multi"
                    TimeAttackEndpoint="dungeon_record/record_time_attack"
                    ReplayTimeoutSeconds="30"
                    BearerToken="primary-token"
                    RandomMatchingStartDelayMs="30000"
                    EnableSecondaryServer="true"
                    SecondaryViewerIdCriterion="1000000000"
                    SecondaryApiServerUrl="https://orchis.cherrymint.live/2.19.0_20220719103923/"
                    SecondaryStateManagerUrl="https://photonstatemanager.cherrymint.live/"
                    SecondaryBearerToken="secondary-token"
                    EnableDiscordIntegration="true"
                    DiscordUrl="https://discordbot.cherrymint.live/bot/"
                    DiscordBearerToken="discord-token"/>
        </Plugins>
    </PluginSettings>
</root>

    The config values have the following meanings:

    Key Explanation
    Name Do not change. Name of the plugin as sent to the Dragalia client.
    Version Plugin version -- the example above will look in Plugins/GluonPlugin/v1/bin for binary files. Can be hot reloaded.
    AssemblyName Do not change. Plugin assembly name.
    Type Do not change. Plugin factory type name.
    ApiServerUrl URL of the main API server. Used to make requests for party data.
    StateManagerUrl URL of hosted room state manager (e.g. DragaliaAPI.Photon.StateManager)
    DungeonRecordMultiEndpoint Endpoint to call on behalf of players when clearing a quest
    TimeAttackEndpoint Endpoint to call when registering a Time Attack clear.
    ReplayTimeoutSeconds The number of seconds players have to confirm whether they want to play again after a clear
    BearerToken Token to embed in Authorization header when making requests to the state manager
    RandomMatchingStartDelayMs The duration in milliseconds to wait for a random matching room (e.g. invasion events) to start when more than one player is present.
    EnableSecondaryServer Whether or not to enable secondary server connections. This allows another API server to host rooms on the same Photon server. Each server must have a distinct viewer ID range, as this is how the plugin determines which server belongs to.
    SecondaryViewerIdCriterion The threshold value at which the viewer ID of a joining player means they are joining from the secondary server. All players with viewer IDs less than this value will be considered as being from the primary server.
    SecondaryApiServerUrl Used instead of ApiServerUrl when a room is in secondary server mode.
    StateManagerUrl Used instead of StateManagerUrl when a room is in secondary server mode.
    SecondaryBearerToken Used instead of BearerToken when a room is in secondary server mode.
    EnableDiscordIntegration Whether to enable requests to a Discord bot for posting active rooms. N.B. due to a bug, setting this to false does not disable Discord integration.
    DiscordUrl The URL of a server to send Discord bot requests to.
    DiscordBearerToken The bearer token to use in the Authorization header when making Discord bot requests.

  4. Update LoadBalancing/GameServer/bin/GameServer.xml.config to increase the maximum property size:

<Limits>
    <Inbound>
        <EventCache>
            <EventsCount>100000</EventsCount>
            <SlicesCount>1000</SlicesCount>
            <ActorEventsCount>100000</ActorEventsCount>
        </EventCache>

        <Properties>
            <MaxPropertiesSizePerGame>510000</MaxPropertiesSizePerGame>
            <MaxPropertiesSizePerRequest>9000000</MaxPropertiesSizePerRequest>
        </Properties>
        <Operations>
        </Operations>
    </Inbound>
</Limits>

  1. Optionally, update bin_Win64/PhotonServer.config and decrease the MinimumTimeout and MaximumTimeout values. These will control the amount of time before a player who stops sending packets is kicked from the room. The defaults cause players to leave after between 10 and 30 seconds of inactivity. For Dragalia, it can be beneficial to decrease this so that 1) AI units take over faster in quests and 2) if a player leaves while the room is loading, other players are not locked in the loading screen waiting for them for too long.

  2. If deploying in production, follow best practices such as:

    • disable debug logging
    • remove the console log appender
    • change the AuthToken from the default on all 3 servers
    • ensure the server-to-server port (4520) is not publicly accessible

Part 2: Configuring the state manager

The state manager application should be comparitively easy to deploy. It is a Docker container that expects to be deployed alongside a redis/redis-stack image. See the docker-compose.yml file in the repository for reference. It does not need to be on the same server as Photon.

It expects an environment variable, PHOTON_TOKEN, to match that which is configured in plugin.config above, so as to authenticate requests from the Photon server. A sample Docker compose file could look like:

version: "3.4"

services:
  photonstatemanager:
    hostname: photonstatemanager
    image: sapiensanatis/dragalia-api-statemanager:latest
    ports:
      - "3000:80"
    environment:
      PHOTON_TOKEN: yourtoken

  redis:
    hostname: redis
    image: redis/redis-stack-server

In appsettings.json configure the following values:

  • $.SeqOptions: set up your Seq logging config, or leave it disabled if you don't want to log to Seq.
  • $.ConnectionStrings.Redis: set up your Redis Stack connection string. The default will suffice if using docker-compose with the default networking.
  • $.RedisOptions.KeyExpiryTimeMins: this can be changed to control the time after which rooms naturally expire in Redis.

Part 3: Configuring the main API server

In the main API appsettings.json, configure the following values in $.PhotonOptions:

  • ServerUrl: the Photon server URL. Must end with :5055 due to Dragalia using a legacy client.
  • StateManagerUrl the Photon state manager URL.

Configure the following environment variables:

  • PHOTON_TOKEN: the same photon token as the plugin and state manager use. Used to authenticate requests from Photon.

Other servers

If you are not using DragaliaAPI / Dawnshard as your main API server, you will need to implement the following endpoints:

  • /heroparam/batch: Get party information based on the list of viewer IDs and party numbers in the request body. See HeroParamService.cs.
  • /matching/get_room_list: Get a list of all open rooms. Typically can call /get/gamelist on the state manager.
    • Additional work must be done by the API server to populate fields such as host lead character. See MatchingService.cs.
  • /matching/get_room_list_by_quest_id: Get a list of open rooms for a quest. Can call /get/gamelist?questId=XXXXX on the state manager.
  • /matching/get_room_name: Get a private room based on the passcode. Can call /get/byid/{id} on the state manager.

Additionally:

  • You must set is_host correctly in /dungeon_start/start_multi, /dungeon/fail, and /dungeon_record/record_multi. The state manager provides an endpoint: GET /get/ishost/<viewerid> returning a response body of true or false ( JSON scalar) to help with this.
  • /dungeon_record/record_multi must be able to accept requests from the Photon server. The Photon server will provide an Authorization Bearer <PHOTON_TOKEN> header, as well as Auth-ViewerId for authentication.
  • To populate helper_list in the record/fail endpoints, you can get a player's current room using GET /ByViewerId/<viewerId>, then map the returned Players with their lead unit / friend info.

Plugin upgrades

v2.0.1 -> v2.1.0

  • Must set is_host correctly in /dungeon/fail

v2.0.0 -> v2.0.1

  • Patch release, no changes required

v1 -> v2.0.0

  • New configuration properties:
    • DungeonRecordMultiEndpoint
    • ReplayTimeoutSeconds
  • Removed configuration properties
    • GameCreateEndpoint
    • GameCloseEndpoint
    • GameJoinEndpoint
    • GameLeaveEndpoint
    • EntryConditionsEndpoint
    • MatchingTypeEndpoint
  • Must set is_host correctly in /dungeon_record/record and /dungeon_start/start
  • Must allow main API server to receive Photon requests to /dungeon_record/record_multi
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